The present invention relates to fluid dispensing tool assemblies for evacuating and charging a fluid into a fluid system and of the general type disclosed in U.S. Reissue Pat. No. RE34,715 and in U.S. Pat. Nos. 4,889,149 and 5,560,407 which issued to the assignee of the present invention. As disclosed in the '149 and '407 patents, such tool assemblies are commonly used to fill automotive-type or motor vehicle cooling systems by first evacuating the cooling system and then charging or filling the system with a predetermined volume of fluid or coolant. Since all of the air in the system is removed during the evacuation cycle, the cooling system is filled completely without residual air pockets. Preferably, the tool assembly also provides for partially filling an overflow bottle or container which is usually connected by a flexible line or hose to the fill neck of the cooling system radiator. Since the overflow bottle is not filled completely, it is not necessary to evacuate the bottle prior to filling the bottle, but preferably, the overflow bottle receives coolant or cooling fluid simultaneously while the cooling system is being evacuated and filled in order to reduce the time of the full cycle.
With any such dispensing tool assembly for evacuating and filling a cooling system, it is desirable for the tool assembly to be compact and lightweight, to be easily attached to a cooling system, and to be simple to remove and replace for servicing. It is also desirable for the tool assembly to have control valves and passages which do not restrict the flow of fluid through the tool assembly so that a high fill rate may be obtained. In addition, the tool assembly should be easily adapted for use with radiator fill necks of different sizes and to provide for partially filling an overflow container or bottle simultaneously while the cooling system is being evacuated and filled with a fluid or liquid coolant. While the charging or dispensing tool assemblies disclosed in the above mentioned patents provide some of these desirable features, none of the tool assemblies provide all of the features.